Popular metric, commonly known as pop met, single row deep groove ball bearings are one of the most common types of ball bearing in use, this is down to their versatility. They are simple in design, suitable for high speeds, non separable, are very robust in operation and require very little maintenance. Deep raceway grooves and the close conformity between the grooves and the balls enable deep groove ball bearings to accommodate axial loads in both directions, even at high speeds.

An open ball bearing does not have any seals or shields; this enables the free flow of oil or grease through the bearing for lubrication purposes. This means that open ball bearings are suitable for use in environments where there is a constant supply of lubrication and very little foreign matter present, e.g. in a gearbox.